(a) Field of the Invention
The present invention relates to a method for fabricating a complex magnetic head including a reproducing magneto-resistance head (MR head) and, more particularly, to a method for fabricating a complex magnetic head including a reproducing head using a MR effect and a recording head using electromagnetic induction.
(b) Description of the Related Art
A complex magnetic head is known in the art which includes a MR head and an inductive (ID) head formed on the MR head in a layered structure. In a practical complex magnetic head, the MR head is used as a reproducing head and the ID head is used as a recording head. The MR head includes a pair of magnetic shield films S1 and S2 opposing each other, and a MR element sandwiched between the magnetic shield films S1 and S2 and separated therefrom by respective magnetic separation layers acting also insulating layers.
The ID head uses the magnetic shield film S2 as a bottom magnetic pole P1, and further includes a coil and a top magnetic pole P2 on one of the sides of the bottom magnetic pole P1 far from the MR element. The coil is sandwiched between a pair of insulator films. The magnetic poles P1 and P2 are layered parallel to each other, and operate for inductive recording using a magnetic field generated in a magnetic gap between these magnetic poles P1 and P2.
With the improvement of the recording density of a magnetic recording disk, the top magnetic pole P2, which defines the recording track width on the magnetic recording disk, is required to have a smaller width at the end face thereof which is disposed on the air bearing surface (ABS) opposing the magnetic recording disk.
A fabrication process of the complex magnetic head includes the steps of forming the bottom magnetic pole P1, forming the coil insulated by insulator films and forming the top magnetic pole P2 for the ID head. In this process, it is difficult to form a small end width of the top magnetic pole P2, because the photoresist frame for defining the shape of the top magnetic pole P2 is formed directly on the insulator film which has a larger height at the center thereof and decreases its height toward the periphery thereof, and yet the end of the top magnetic pole P2 is located in the vicinity of the smaller-height periphery. In this situation, the lower limit of the end width of the top magnetic pole P2 defining the recording track width is about 2 micrometers.
Patent Publication JP-A-7-225917 proposes reduction of the end width of the top magnetic pole P2 by using the process including the step of forming only the end portion of the top magnetic pole P2 before forming the coil covered by the insulator film, followed by the step of forming the rest of the top magnetic pole P2 and the coil. The proposed technique achieves a smaller end width of the top magnetic pole P2 as low as about 1 micrometer.
The inventor fabricated the complex magnetic head including a MR head and an ID head by using the proposed technique. However, the complex magnetic head thus fabricated had the problems described below.
When the end portion of the top magnetic pole was formed by an economic frame plating method, the photoresist frame for the end portion of the top magnetic pole P2 had a shape of character "U" because the end portion is defined at the zero position for a throat height. The throat height is generally defined as the height measured from the periphery of the insulator layer for the coil and the ABS.
As a result, a puddle plating step generally used for forming the top magnetic pole involved poor flow of the plating liquid because of the shape of "U" which does not allow a sufficient flow for the plating liquid due to the closed bottom thereof. Thus, variations in composition of the plated film resulted and the magnetic property of the end portion of the top magnetic pole was degraded, although the magnetic property of the end portion is most important in the ID head. The presence of degradation or variations in the end portion of the top magnetic pole will reduce the throughput of the complex magnetic head.
In addition, a large variation is observed in the throat height itself at the end portion of the top magnetic pole. The control of the throat height is generally important to assure the recording performance of the ID head.
Thus, the complex magnetic head fabricated by the proposed technique did not provide sufficient performance and throughput for the complex magnetic head.